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stk::FormSwep Class Reference

STK sweepable formant filter class. More...

#include <FormSwep.h>

Inheritance diagram for stk::FormSwep:
stk::Filter stk::Stk

Public Member Functions

 FormSwep (void)
 Default constructor creates a second-order pass-through filter.
 
 ~FormSwep ()
 Class destructor.
 
void ignoreSampleRateChange (bool ignore=true)
 A function to enable/disable the automatic updating of class data when the STK sample rate changes.
 
void setResonance (StkFloat frequency, StkFloat radius)
 Sets the filter coefficients for a resonance at frequency (in Hz). More...
 
void setStates (StkFloat frequency, StkFloat radius, StkFloat gain=1.0)
 Set both the current and target resonance parameters.
 
void setTargets (StkFloat frequency, StkFloat radius, StkFloat gain=1.0)
 Set target resonance parameters.
 
void setSweepRate (StkFloat rate)
 Set the sweep rate (between 0.0 - 1.0). More...
 
void setSweepTime (StkFloat time)
 Set the sweep rate in terms of a time value in seconds. More...
 
StkFloat lastOut (void) const
 Return the last computed output value.
 
StkFloat tick (StkFloat input)
 Input one sample to the filter and return a reference to one output.
 
StkFramestick (StkFrames &frames, unsigned int channel=0)
 Take a channel of the StkFrames object as inputs to the filter and replace with corresponding outputs. More...
 
StkFramestick (StkFrames &iFrames, StkFrames &oFrames, unsigned int iChannel=0, unsigned int oChannel=0)
 Take a channel of the iFrames object as inputs to the filter and write outputs to the oFrames object. More...
 
- Public Member Functions inherited from stk::Filter
 Filter (void)
 Class constructor.
 
unsigned int channelsIn (void) const
 Return the number of input channels for the class.
 
unsigned int channelsOut (void) const
 Return the number of output channels for the class.
 
virtual void clear (void)
 Clears all internal states of the filter.
 
void setGain (StkFloat gain)
 Set the filter gain. More...
 
StkFloat getGain (void) const
 Return the current filter gain.
 
StkFloat phaseDelay (StkFloat frequency)
 Return the filter phase delay at the specified frequency. More...
 
const StkFrameslastFrame (void) const
 Return an StkFrames reference to the last output sample frame.
 
- Public Member Functions inherited from stk::Stk
void ignoreSampleRateChange (bool ignore=true)
 A function to enable/disable the automatic updating of class data when the STK sample rate changes. More...
 

Additional Inherited Members

- Static Public Member Functions inherited from stk::Stk
static StkFloat sampleRate (void)
 Static method that returns the current STK sample rate.
 
static void setSampleRate (StkFloat rate)
 Static method that sets the STK sample rate. More...
 
static std::string rawwavePath (void)
 Static method that returns the current rawwave path.
 
static void setRawwavePath (std::string path)
 Static method that sets the STK rawwave path.
 
static void swap16 (unsigned char *ptr)
 Static method that byte-swaps a 16-bit data type.
 
static void swap32 (unsigned char *ptr)
 Static method that byte-swaps a 32-bit data type.
 
static void swap64 (unsigned char *ptr)
 Static method that byte-swaps a 64-bit data type.
 
static void sleep (unsigned long milliseconds)
 Static cross-platform method to sleep for a number of milliseconds.
 
static bool inRange (StkFloat value, StkFloat min, StkFloat max)
 Static method to check whether a value is within a specified range.
 
static void handleError (const char *message, StkError::Type type)
 Static function for error reporting and handling using c-strings.
 
static void handleError (std::string message, StkError::Type type)
 Static function for error reporting and handling using c++ strings.
 
static void showWarnings (bool status)
 Toggle display of WARNING and STATUS messages.
 
static void printErrors (bool status)
 Toggle display of error messages before throwing exceptions.
 
- Static Public Attributes inherited from stk::Stk
static const StkFormat STK_SINT8
 
static const StkFormat STK_SINT16
 
static const StkFormat STK_SINT24
 
static const StkFormat STK_SINT32
 
static const StkFormat STK_FLOAT32
 
static const StkFormat STK_FLOAT64
 
- Protected Member Functions inherited from stk::Stk
 Stk (void)
 Default constructor.
 
virtual ~Stk (void)
 Class destructor.
 
void addSampleRateAlert (Stk *ptr)
 Add class pointer to list for sample rate change notification.
 
void removeSampleRateAlert (Stk *ptr)
 Remove class pointer from list for sample rate change notification.
 
void handleError (StkError::Type type) const
 Internal function for error reporting that assumes message in oStream_ variable.
 

Detailed Description

STK sweepable formant filter class.

This class implements a formant (resonance) which can be "swept" over time from one frequency setting to another. It provides methods for controlling the sweep rate and target frequency.

by Perry R. Cook and Gary P. Scavone, 1995–2014.

Member Function Documentation

void stk::FormSwep::setResonance ( StkFloat  frequency,
StkFloat  radius 
)

Sets the filter coefficients for a resonance at frequency (in Hz).

This method determines the filter coefficients corresponding to two complex-conjugate poles with the given frequency (in Hz) and radius from the z-plane origin. The filter zeros are placed at z = 1, z = -1, and the coefficients are then normalized to produce a constant unity gain (independent of the filter gain parameter). The resulting filter frequency response has a resonance at the given frequency. The closer the poles are to the unit-circle (radius close to one), the narrower the resulting resonance width. An unstable filter will result for radius >= 1.0. The frequency value should be between zero and half the sample rate.

void stk::FormSwep::setSweepRate ( StkFloat  rate)

Set the sweep rate (between 0.0 - 1.0).

The formant parameters are varied in increments of the sweep rate between their current and target values. A sweep rate of 1.0 will produce an immediate change in resonance parameters from their current values to the target values. A sweep rate of 0.0 will produce no change in resonance parameters.

void stk::FormSwep::setSweepTime ( StkFloat  time)

Set the sweep rate in terms of a time value in seconds.

This method adjusts the sweep rate based on a given time for the formant parameters to reach their target values.

StkFrames & stk::FormSwep::tick ( StkFrames frames,
unsigned int  channel = 0 
)
inlinevirtual

Take a channel of the StkFrames object as inputs to the filter and replace with corresponding outputs.

The StkFrames argument reference is returned. The channel argument must be less than the number of channels in the StkFrames argument (the first channel is specified by 0). However, range checking is only performed if STK_DEBUG is defined during compilation, in which case an out-of-range value will trigger an StkError exception.

Implements stk::Filter.

154 {
155 #if defined(_STK_DEBUG_)
156  if ( channel >= frames.channels() ) {
157  oStream_ << "FormSwep::tick(): channel and StkFrames arguments are incompatible!";
158  handleError( StkError::FUNCTION_ARGUMENT );
159  }
160 #endif
161 
162  StkFloat *samples = &frames[channel];
163  unsigned int hop = frames.channels();
164  for ( unsigned int i=0; i<frames.frames(); i++, samples += hop )
165  *samples = tick( *samples );
166 
167  return frames;
168 }
StkFrames & stk::FormSwep::tick ( StkFrames iFrames,
StkFrames oFrames,
unsigned int  iChannel = 0,
unsigned int  oChannel = 0 
)
inline

Take a channel of the iFrames object as inputs to the filter and write outputs to the oFrames object.

The iFrames object reference is returned. Each channel argument must be less than the number of channels in the corresponding StkFrames argument (the first channel is specified by 0). However, range checking is only performed if STK_DEBUG is defined during compilation, in which case an out-of-range value will trigger an StkError exception.

171 {
172 #if defined(_STK_DEBUG_)
173  if ( iChannel >= iFrames.channels() || oChannel >= oFrames.channels() ) {
174  oStream_ << "FormSwep::tick(): channel and StkFrames arguments are incompatible!";
175  handleError( StkError::FUNCTION_ARGUMENT );
176  }
177 #endif
178 
179  StkFloat *iSamples = &iFrames[iChannel];
180  StkFloat *oSamples = &oFrames[oChannel];
181  unsigned int iHop = iFrames.channels(), oHop = oFrames.channels();
182  for ( unsigned int i=0; i<iFrames.frames(); i++, iSamples += iHop, oSamples += oHop )
183  *oSamples = tick( *iSamples );
184 
185  return iFrames;
186 }

The documentation for this class was generated from the following file:

The Synthesis ToolKit in C++ (STK)
©1995--2014 Perry R. Cook and Gary P. Scavone. All Rights Reserved.